Stress path dependent stress-strain behaviour of micaceous sands

Abstract

The stress-deformation behaviour of any soil depends on a number of factors including stress path followed during shear and its mineralogical composition. In order to determine actual stressdeformation behaviour of sands, it is desirable that the composition of the specimen tested and the stress path followed during the laboratory test are identical to those occuring in situ. Sands are primarily composed of quartz. Mica is often present in sands. A large portion of research on engineering behaviour of sand has been concentrated on quartz and little attention has been paid to the behaviour of micaceous sands. However, in many projects, it becomes necessary to predict stress-deformation behaviour of micaceous sands. This study presents thecresults of tests on a sand containing various percentages of mica under different stress paths') Drained triaxial tests on sands containing different percentages of mica along different stress paths are performed. Results of these tests are presented herein. The mica content of the samples tested are 2.5%, 4.0%, and 6.0%. The specimens are tested at confining pressures of 55 kPa, 75 kPa, 100 kPa and 210 kPa. using these test results, the effect of mica content on maximum and minimum densities, maximum and minimum void ratios, strength parameters, and volume change behaviour are studied. The influence of stress path on the strength parameters and volume change are also examined. It is observed that the maximum and minimum densities of the samples decreases with increasing mica content. conversely maximum and minimum void ratios increase with mica content. Increasing mica content results in reduction of the value of the angle of internal friction. It is also observed that the angle of internal friction depends on stress path followed during shear. The initial tangent modulus is found to increase with decreasing mica content. The initial tangent modulus is also found to depend on stress path. Mica content has no influence on both axial and volumetric strains. Both of these strains are found to depend on stress path followed.